This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. There is increasing interest in the development of computational methods to analyze fluorescent microscopy images and enable automated large-scale analysis of the subcellular localization of proteins. Determining the subcellular localization is an integral part of identifying a protein's function, and the application of bioinformatics to this problem provides a valuable tool for the annotation of proteomes. Training and validation of algorithms used in image analysis research typically rely on large sets of image data, and would benefit from a large, well-annotated and highly-available da-tabase of images and associated metadata. Results: The Yeast Resource Center Public Image Repository (YRC PIR) is a large image database depicting cells and the subcellular localization of proteins. The YRC PIR contains 517,642 TIFF images from nearly 80,000 separate localization experiments and their associated experimental data. All images and associated data are searchable, and the results browsable, through an intuitive web interface. Search results may be saved as customized downloads, or the entire dataset may be downloaded.